Forced Genocide
by whovianmidget
Summary: After yet another pacifist run, Frisk promised Sans that she would never reset again. So when Sans wakes up in his room in Snowdin, he is angry. But this time, Frisk takes much longer in the ruins that she usually does. And when she finally does enter Snowdin, Frisk is covered with dust. Frisk had started the Genocide route, but why? Read to find out. T for psychological torture.
1. chapter 1-Prologue

**Hey Guys! this will be my first ever multi-chapter fic for undertale. It will take place right after the Pacifist Route. it is rated T for** **psychological** **torture. this fic will be around 9 chapters. it will hopefully be full of angst and hurt comfort, so yay. everything that is in _italic_ will be a flashback, most of them from Frisks POV, and one of them from Sans's. Also, in this fic, Frisk is a girl around the age of fifteen.**

 **welp, that all you really need to know for this fic. I hope you enjoy, and please review if you like it!**

* * *

Chapter 1-prologue

 _Frisk stared at the same sunset she had seen so many times. It was such a beautiful sight, and she knew that the others had thought so as well. She turned to look at her new friends standing next to her, all of them happy to be on the surface that they had waited far too long to reach._

 _Well, all of them except one._

 _Frisk knew that Sans hated every time she reset. But every time she did reset, she was only trying to make the best ending for everyone. She had tried so hard to save Asriel, and maybe even Chara. But after doing the same exact route so many times, she was beginning to think that maybe they didn't want to be saved._

 _Besides, every time she did reset, she could clearly see that Sans getting less and less happy._

 _Maybe it was time to stop. This was as good as it was going to get. It was time to continue from now on._

 _"Sans?" She said walking around her new mom to talk to the short skeleton. Sans tiredly turned to look at the kid._

 _"sup kiddo?" He said, trying to keep the mood up._

 _"I wanna talk to you." Frisk said, and Sand looked a little weary, but followed Frisk further down the mountain anyway. Frisk then looked at Sans 'dead' in the eye sockets. "I'm not going to do it again." She said, looking at her friend hopefully._

 _Sans blinked in response. "come again?" he said, trying not to get his hopes up. Frisk sighed._

 _"I promise I will never reset again unless the situation gets so bad that I have no choice not to." Frisk said, saying every word slowly and clearly._

 _Sans blinked. And then blinked again. And then he smiled more than Frisk even thought possible, and she could even see real joy in his eyes for once._

 _For the first time in a long time, Sans was truly happy._

* * *

 _Sans blinked the sleep out of his non-existent eyes, and sat up happily. The first night of many without a reset. He yawned, stretching his arms over his head, and looked around the room._

 _And then he stopped dead._

 _This wasn't the room from the hotel on the surface. He was back in his dreadful room in snowdin._

 _Sans couldn't believe it. Frisk had promised not to reset. That good-for-nothing kid looked him straight in the eyes and lied to him._

 _And Sans had never been more angry._

* * *

 _Frisk woke up like usual on the bed of flowers near the ruins. At first she didn't notice the change in scenery caused by the reset, but as soon as she did, she nearly had a panic attack. She had promised to never reset, and she meant it. Unless she could reset in her sleep, this wasn't caused by her. She sighed. Sans was going to be so mad. Frisk herself was mad. She had been ready to move forward just as much as Sans was._

 _She stood up and prepared herself from either Flowey yelling at her or being attacked ruthlessly by him._

 _But she never even made it that far._

 _She was walking towards the huge purple door like she always did, but before she could even walk through it, a very tall man appeared in front of her. He seemed to be a skeleton, but his black robe seemed to flow endlessly into the darkness. He didn't even seem real._

 _Without even saying anything, the strange man reached out his hands, and before Frisk could even yell for help, he grabbed her tight and teleported away._

* * *

(Present day)

Sans was starting to worry. Frisk had never taken this long before. Sometimes it took a day at most, but it had been weeks since the reset. Even though Sans was still pissed at the kid, his worry for her had started to outweigh that.

Currently he was sleeping at his post like usual, just waiting for the kid to come. But he had almost given up hope that Frisk would come at all all.

And that's when he had woke up to the sound of a stick snapping.

Frisk was coming. Finally.

Sleepily, Sans got up and followed the trail of footprints. He prepared his usual woopie cushion in the hand trick. Looking ahead, he saw that Frisk had stopped at the gate like she did every time.

Sans walked up behind her.

"h u m a n," he started, but before he could finish his usual little speech, Frisk turned around and held out her hand. Sans shook it in response, the whoopie cushion farting loudly.

Sans forced a laugh, and waited for Frisk to do the same. "hey kid this is usually your cue to laugh." Frisk didn't even bat an eye.

"Alright, let's cut the act." He said, his left eye flashing blue, "why did you reset?"

Again, Frisk didn't do anything. She just stood her. Sans's eye stopped flashing, And he studied her. Something about her seemed different. Frisk eyes were looking at nothing. She had a dead look in her eyes that scared Sans. This wasn't Frisk, not really.

And then he noticed the dust. Frisk was practically covered in it. Sans had known Frisk for a long time, and for any of the routes, she had never killed anyone. Maybe on her first route she accidentally killed a froggit out of defence, but never enough to be covered this much in dust.

Something was really wrong.


	2. Chapter 2- Bad Time

**A/N Hello again! so this is the second chapter, and the only reason I'm updating it the same day as the first one is cuz i think it'll make more sense with this chapter. But i probably wont be updating it this recently anymore, i will post at most every week, but sometimes i might post earlier, and i might sometimes post later, with school and everything. ya know how it is. anyway, please R &R! i really enjoy hearing your feedback, but please be nice!**

* * *

 _Frisk woke up in a strange room, everything around her either a bright white or a dull grey. She was laying on a white bed, wrists and ankles tied to each side. She couldn't move._

 _Suddenly the door in front of the bed opened, creaking as a dark figure walked in the room._

" _ah_ " _said the dark figure in a strange language. Frisk didn't know how she could understand the words. "I see you have awoken." the man looked like he was the same that had captured her, the same pale skeleton with the black robe flowing into eternity._

" _Who are you?" Frisk yelled. "Why did you take me here?!" The black figures dark smile seemed to grow wider._

" _I am Gaster. I have seen you go through many pacifist timelines. It's rather boring, not killing, isn't it? I have no idea how you manage." The man, Gaster, walked towards her. "Besides, I want revenge. And you are going to help me get it."_

 _Frisk tried to back away from Gaster, but the ties around her wrists and ankles prevented her from doing so. "What do you mean?" She asked timidly._

 _Gasters grin grew even wider. "I'm going to make you kill everyone."_

* * *

Sans watched as Frisk killed monster after monster. Getting more and more dust all over her every time she swung that toy knife around. Papyrus was attempting to capture them with puzzles like he did every route, but this time Frisk didn't even play along. She just walked right past every single one of them.

Eventually, It was almost time for her to fight Papyrus. Sans knew no matter how much he tried to get his brother to not fight the human, Papyrus would still go up against the kid. So, after the 'Gauntlet of Deadly Terror", Sans stopped Frisk before she could walk past.

"if you keep going the way you are now, _you're gonna have a bad time._ " Sans's eyes hollowed out like they did whenever he got serious or angry. But Frisk just looked on ahead and walked past him, ignoring Sans completely, dead eye's almost glowing in the snow.

* * *

 _Gaster quickly untied Frisk's bonds that were keeping her from moving, then harshly grabbed her by the arm and practically dragged her into a separate room. Inside said room, there was a chair with a weird looking helmet. Gaster shoved Frisk into the chair and tied her up again. He then put on the weird shaped helmet, which covered over Frisk's eyes, making it so she couldn't see._

" _What are you doing?" Frisk asked. It had been days since the skeleton had kidnapped her, but he hadn't done anything much except leave her alone and give her minimal amounts of food. The sudden change in routine made Frisk think his plan to 'force her to kill everyone' was actually starting. Not that it would work. There was no way that Frisk could ever hurt her friends._

 _Gaster didn't say anything and she heard him push buttons on the farther side of the room. Suddenly Frisks vision went white, it seemed as if the helmet thingy was activating. Suddenly she was in a cute little house in the ruins. Toriels house. For a split second Frisk thought she had escaped, or that it was all just a bad dream. But right then, a fireball hit her right in the back. Frisk screamed in pain, turning around to see Toriel, her mother figure, look her dead in the eye's and shoot another fireball at the young girl. Frisk only barely dodged out of the way._

" _You are a stupid, stupid child," Toriel said, eyes fierce with anger. "I don't even know why I keep you around." Toriel prepared yet another magic attack, and Frisk soon felt fire surround her body._

" _Mom!" she yelled, eye's beginning to fill with tears. "Somebody help!"_

 _She knew this was a dream, or a simulation, or something Gaster was doing to try to make Frisk fight her family. But Frisk wouldn't fight back. She refused to fight back._

 _But it was just_ so real.

* * *

This was it. Frisk was about to fight Papyrus. Sans was almost too afraid to watch, but he couldn't look away. Papyrus and started talking to the human child, trying to tell Frisk that 'you can do better' and 'I believe in you!'

Frisk had started walking towards his brother, and of course innocent Papyrus would take that as a hug of acceptance. Sans had tried to run to his brother to protect him, but he was too late. By the time he had gotten there, Papyrus was already dust.

Sans didn't know why Frisk had done this. This wasn't her. _Couldn't_ be her. But She had killed his brother. The only person he really cared about. Sans didn't care what caused Frisk to do this. Right then and there, Sans both made and broke a promise.

Screw protecting the kid.

She was gonna have a bad time.


	3. Level of Violence

_Frisk screamed as boned penetrated her body, and she felt her soul cracking to pieces. Just like usual when she died in these simulations, she woke up in Gasters lab, breathing heavily._

 _Or… was it the other way around? Frisk couldn't tell what was real anymore. Both situations were pretty bad. In one, she was practically starved and experimented on, and in the other, all her friends did was attack her. In both realities, she was alone._

 _She could hear Gaster walking around through her simulation helmet thing. It sounded as if he was pushing more buttons to start up yet another simulation. Frisk then heard the whirring of the machine, and then everything went white._

 _She woke up in snowdin, and she recognized it as the place where she fought Papyrus. She walked further into the fog hoping once again that she might be free._

 _But no._

 _As soon as she saw Papyrus, He turned around and shot her directly in the heart. He looked angry at her, just as everyone else had. It was a strange look for Papyrus._

 _He continued to hit her again and again, endless bone attacks hitting at her sore soul. Frisk tried to run away, but Papyrus would tug her soul back to the fight._

 _She started screaming in pain, tears streaming down her face. She couldn't handle it anymore._

 _She called for someone, anyone, to help._

 _But nobody came._

* * *

Frisk was going around killing monster after monster. She managed to kill 18 within 10 minutes. Sans glared at the child he once called a friend. They were getting close to Undyne. Knowing the fish monster, it would take Frisk a while to beat her. For a monster, Undyne sure had a lot of determination.

Suddenly there was a loud _yo!_ And Sans looked to see monster kid greeting Frisk with his usual innocent as soon as the young monster realized what Frisk had done, he was stupid enough to try to attack her. Sans had to close his eyes as Frisk threw a fatal blow to Monster Kid.

But instead of hearing a monster child turning to dust, he heard the sound of metal hitting metal.

Frisk had hit Undyne.

* * *

 _Frisk had rolled herself into a protective ball, shielding the majority of her body from getting hit with hard bones. But that's when she heard a voice._

" _hey bro, why don't you stop hitting the poor kid?" Frisk recognized as Sans had spoken to Papyrus, stopping him from hitting her anymore. Frisk was relieved. Finally, someone stopped hurting her. She almost this torture had come to an end. She looked up at the skeleton brothers, thinking she was finally free and safe._

 _But how wrong she was._

" _let me give the final blow."_

 _Sans's right eye turned a light blue, and several bones came out of nowhere. Frisk's stomach dropped. Sans was even more powerful than Papyrus._

 _She dodged as much as she could, which wasn't much. When Sans had stopped his attack, Frisk was just a pile of flesh on the ground. She heard Sans walk up to her and summon a single bone. Her HP was low enough that one bone would kill her instantly._

 _But she was tired of dying._

 _As she heard Sans lift the bone over his head to deliver the final blow, she suddenly stood up and spun around, pulling out a toy knife from her inventory. She swung the knife faster than either Sans or she could blink._

 _Sans looked at her, shocked._

 _And then he turned to dust._

 _Papyrus screamed in agony, but Frisk didn't hear anything. She had just killed someone she thought to be a friend. She took a step back, in shock. She could feel the change in her LV, the strange sense of violence surging through her veins. It felt wrong._

 _But… it also felt.. Good?_

 _LV 2_


	4. The Undying

**Hi. Sorry this took so long, i was really busy. But ill try to update sooner if i can.**

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Chapter 4

Frisk hit Undyne.

Frisk was going to kill an innocent kid, but Undyne shoved him out of the way and took the hit for him. Sans thought she was done for, it was a pretty nasty hit. He wasn't surprised when she started turning to dust. He looked away, not wanting to see another one of his friends die.

But the sound of dust never came. He turned back to the scene only to see Undyne, alive as ever, with a determined look on her face. Sans was shocked. Wasn't she dust a moment ago?

Undyne grinned. "You're going to have to try a little harder than that." Sans watched as a fight unfolded, spears flying from every direction towards Frisk, and Sans grinned. This was going to give Frisk a run for her money.

* * *

 _Frisk sat in her cell motionless. It had been days since Gaster put her in a simulation. It was probably because they were 'making progress.'_

 _It was three simulations ago when she killed Sans. The simulation after that, Frisk was sent to hotland. Alphys and Mettaton attacked her ruthlessly. It seemed that Always had some pretty strong magic of her own. Frisk tried to resist it, but it hurt so much. She had pulled out her knife and swiped, killing Alphys in one hit._

 _Her LV rose to 4 after that._

 _The latest simulation was the core. Mettaton attacked her again in that one, but she was able to kill him, too. That kill had gotten her a huge raise in LV, she was now at LV 10._

 _And it felt_ great.

 _That was the only thing on her mind while she waited for Gaster to send her through another simulation. The thirst to kill. The want to hurt._

 _She didn't move when her cell door finally opened. Gaster dragged her out of the cell, and she followed willingly. This time, before he shoved Frisk into the chair and put her into another simulation, he decided to try something._

 _He got out a flashlight and turned it on. He then waved it in front of her face, wanting to see if that got a reaction out of her._

 _It didn't._

 _He decided to try something more drastic. He pulled out a small knife, and slashed Frisks wrist. She didn't even flinch. Quickly, he wrapped the wound before it took off too much of her HP._

 _Then, he grabbed Frisk and shoved her into the usual chair, starting yet another simulation._

 _Frisk was sent to Asgore's castle. Everyone was there, Asgore, Toriel, Undyne, Alphys, Papyrus, and Sans._

 _It didn't take long for Frisk to realize that, this time, it was a memory. Not a simulation. It was just like she remembered it, everyone had come to stop Asgore from fighting her. They all met Toriel, and everyone was happy._

 _But this time, it wouldn't end like it always does._

 _Frisk pulled out her Toy Knife, and slashed Asgore. His defence was down completely, so it took one hit. She smiled, feeling her LV get even higher. Turning around, she saw that everyone was in complete shock._

" _My child…!"_

" _WHAT HAPPENED TO ASGORE?"_

" _You little PUNK!"_

 _Frisks grin grew wider, this was going to be good._

 _She went for Toriel first, She was easy enough. Alphys, who was standing in fear, was next. Undyne had put up a fight, but Frisk, who was now at LV 15, was too much for her. She turned to her next target._

 _Papyrus._

 _She ran to him, and slashed her knife. But suddenly her soul turned blue, and she was thrown to the ceiling. Hundreds of bones came rushing at her, she barely made it out of the attack alive. She looked at her stats._

 _1/70 HP. The attack hit her hard. There was no way the attack was from Papyrus, he wasn't strong enough for that. That only left-_

" _Not my brother, you-" Sans was cut off by Frisk tumbling at him. She slashed, but another skeleton jumped in front of her new target._

 _Papyrus staggered back, already starting to dust after that hit. It seems that Papyrus cared for Sans as much as Sans did him. She grinned at the raise in LV, Papyrus was pretty strong. She was now at LV 19._

 _She didn't even have time to turn to Sans before she heard very loud blaster things fire up, and shoot straight at her._

 _The last thing she felt before waking up in Gasters lab was her soul shattering into a million peices._

* * *

Sans was wishing he was closer to the fight, because this is obviously the hardest one since Frisk started this route. She had already died about 20 times, and Sans was getting hopeful that she would never get past Undyne the Undying.

But it seemed he was wrong. Frisk had practically memorized the fight, dodging the majority of spears expertly. Soon, she had delivered the final hit to Undyne. He was to far away to hear what she said before she turned to dust for the last time.

Frisk left immediately for Hotland, and Sans followed. She began to kill monster after monster yet again. It wasn't long before she had killed over 40 monsters in the area, and now everyone was either dead, or evacuated.

Well, except Mettaton, that is. Sans was prepared for another long battle, knowing that he was a pretty good fighter.

He should've realized that Frisk was stronger. She got him in one hit.

By now, she would be at LV 19. That was enough for his karmic retribution to harm her enough. Besides, there was no one left for her to kill anyway, aside from Asgore.

It seems that the kid was in for a bad time soon.

* * *

 **let me know if you liked it!**


	5. Forced Genocide

It was time.

Frisk had walked into the judgement hall, not seeing Sans yet.

He was ready. It was time for judgment. Time for the kid he once called friend to pay for all her sins. Time for him to get justice for all the people lost because of what she did.

Frisk had walked up close enough to finally spot him. She didn't look surprised to see him.

His eye flashed a cyan blue, and Frisks soul suddenly turned blue.

"Heya." He said coldly. "You've been busy, huh?..."

Frisk smirked. The first real emotion she had shown sense she started this awful route. Sans glared and threw her against the ceiling.

"Let's just get to the point."

The world turned black and white around him.

"Birds are singing flowers are blooming…"

 _ ***you feel like you're in for a bad time.**_

* * *

 _Frisk didn't register when Gaster entered the cell. She didn't register when he practically dragged her to a different room then usual._

 _She didn't register almost everything now. Unless it involves killing, she didn't notice anything about the world around her. By now, Gaster must have cut her wrists dozens of times, each time a little harsher, a little deeper, but never enough to be fatal. But no matter how many times or how much he did it, she never registered._

 _Gaster started talking in his weird language. "Frisk." He said fiercely, "it is time for you to leave. Time for me to get my revenge."_

 _Frisk looked up at her captor with glowing red eyes. She smirked. "All I want is to kill."_

 _Gasters wide grin grew. "Child, that is all I want for you."_

* * *

Sans watched as Frisk died for the 9th time. Her soul shattered as it always did, and then moments later, she was back at the beginning of the hall, and the fight started again.

Sans could tell she was getting better, he could tell that she was memorizing patterns. He knew eventually she was going to beat him.

But he wasn't going to stop. He couldn't afford not to care anymore.

* * *

 _Frisk had appeared in the room at the beginning of the underground, near the flower patch she always woke up on, she knew what was next, and she was prepared for it._

 _It didn't matter anyway. Whoever or whatever got in her way, she would kill everyone. Her thirst to kill was too great._

 _And because of her, the underground would run empty,_

* * *

Death.

That's all she was. The death of her attacker's, the death of her friends, the death of the underground,

The death of herself.

They hurt her. They burned her. They killed her.

So she killed them.

Death.

Kill.

Pain.

That's all she thought of. She didn't remember her name. She didn't remember why they all needed to die.

Now there was only three left.

The skeleton.

The king.

And the flower.

Then it will all be complete.

 _ ***just keep attacking.**_

 _ ***he can't dodge forever.**_

And that's exactly what she did.

 _ ***you are filled with determination.**_

* * *

Sans dodged attack after attack, refusing to get hit. He couldn't let Frisk win.

At this point, his plan was to force Frisk to give up and reset. It didn't seem to be working.

The Frisk he new before this route was kind. Compassionate. Determined to do good.

The Frisk he knew would never do this.

It was his turn again, and he sent a complex pattern of bones toward his opponent. She dodged them perfectly.

Her turn.

She jumped straight to him, knife in hand. He masterfully dodged the attack.

But this time he saw something.

On her arm were light scars, some longer than others. At first, his thought were that they were self inflicted, and he nearly had a heart attack. But then logic came through his head. The scars were on her dominant hand, so she wouldn't have done it to herself. And the majority of them were recent too. And sense he hadn't seen anybody actually harm her sense she entered Snowden, logically that meant:

Someone hurt Frisk.

Someone made her this way.

This was a Forced Genocide.


End file.
